Carburation devices for internal combustion engines



Aug. 29, 1961 A. L. MENNESSON CARBURATION DEVICES FOR INTERNAL COMBUSTION ENGINES Filed May 26, 1960 3 Sheets-Sheet 1 INVEN TOR Gun/rs Zmir Ma mvrrswv ,M; ATTURNE s 1961 A. 1.. MENNESSON 2,998,232

CARBURATION DEVICES FOR INTERNAL COMBUSTION ENGINES Filed May 26, 1960 s Sheets-Sheet z INVE N TOR dm/n: oui: Mswvsssmv A TTORNEYJ Aug. 29, 1961 A. MENNESSON 2,998,232

CARBURATION DEVICES FOR INTERNAL COMBUSTION ENGINES Filed May 26, 1960 3 Sheets-Sheet 3 ATTORNEYS United States Patent Ofiice 2,998,232 Patented Aug. 29, 1961 2,998,232 CARBURATION DEVICES FOR INTERNAL COMBUSTION ENGINES Andr Louis Mennesson, Neuilly-sur-Seine, France, as-

signor to Societe 'Industrielle de Brevets et dEtudes S.I.B.E., Neuilly-sur-Seine, France, a society of France Filed May 26, 1960, Ser. No. 31,889 Claims priority, application France May 30, 1959 13 Claims. (Cl. 261-36) The present invention relates to carburation devices working normally by continuous injection of fuel into the induction pipe of an internal combustion engine downstream of the throttle valve provided in said pipe, said devices being of the kind where a pressure regulator, controlling a leak or bleed passage of variable cross-section, varies the pressure of the fuel in the conduit through which it is conveyed to the injection orifice (or orifices) in the same manner as the flow rate of air circulating in said pipe. This regulator is itself fed with fuel from a continuous flow pumping system under a pressure higher than that Which is to be determined by said regulator and said air flow rate is evaluated by the suction existing in a venturi passage provided in the induction pipe upstream of the throttle valve.

A problem existing in such carburation devices and which has not yet been fully solved consists in achieving a suitable feed of the internal combustion engine under idling running conditions.

In order normally to shield the fuel injecting means from the influence of the suction existing in the induction pipe downstream of the throttle valve thereof, the injection on'fice is generally arranged to open into a chamber which normally communicates on the one hand with the external atmosphere through a channel of relatively great cross-section, and on the other hand with the induction pipe through an orifice of small dimension but still greater than that of the injection orifice, these two orifices being mounted in line with each other so that the jet of fuel passes through this second orifice to penetrate into the induction pipe. Otherwise, it would be necessary to make use of injection orifices of such small dimensions that the maximum rate of flow, at high speeds of the engine, would require excessive feed pressures. Anyway, the flow rate of these injectors during the idling running periods is extremely low and requires a feed pressure of the order of only some grams per square centimeter.

Now, it is very diflicult to provide a pressure regulator which is capable of determining such a pressure in a very accurate manner. Furthermore, when the engine is mounted on a vehicle, the pressure of the fuel upstream of the injection orifice changes to a considerable degree when the vehicle is inclined or even when the fuel which circulates through the conduits of the carburation device is subjected to accelerations, which modifies the flow rate of fuel under idling running conditions whatever be the qualities of the pressure regulator and which may cause the engine to stall by lack or excess of fuel.

The object of the present invention is to obviate these drawbacks.

It consists chiefly in providing the carburation devices of the kind above referred to with means capable, when the conditions are close to idling running of the engine, of transforming the pressure regulator into a constant level chamber system so that the fuel is then introduced through the usual injection orifice or orifices into the induction pipe essentially by the effect of the suction existing in said pipe.

Other features of the invention will become apparent in the course of the following detalied description of some specific embodiments thereof, with reference to the accompanying drawings given merely by way of example and in which:

FIGS. 1 and 2 are diagrammatic elevational views with parts cut away showing a carburation device made according to the invention, respectively in idling running position and in a position corresponding to an intermediate opening of the throttle valve.

FIGS. 3 to 6 show modifications of some details of the device of FIGS. 1 and 2.

FIG. 7 shows a portion of a carburation device similar to that of FIG. 1 but including other elements.

The carburation device includes an induction pipe 1 through which air circulates in the direction of arrow F and which is provided with a throttle valve 2 carried by a control spindle 3. A main venturi passage 4 and possibly an auxiliary venturi passage 5 disposed coaxially in the first one are located in induction pipe 1 upstream of throttle valve 2. Fuel is fed from a tank 6 by means of a continuous flow pump 7 the delivery pressure of which is higher than that to be determined, at the speed that is considered, by the pressure regulator, which will be hereinafter described, the delivery rate of this pump being superabundant and controlled by a calibrated orifice 8 provided in the delivery conduit 9 of the pump. This conduit is connected with pressure regulator 10 which is housed in a casing 11. This regulator, which is itself connected through a conduit 12 with an injector 13, controls a leak passage of variable section in such manner that the excess of fuel flows back to tank 6 through a channel 14 of large cross-section. Casing 11 is placed in communication with the atmosphere either directly or, as shown by FIGS. 1 and 2, through the air intake 15 of the carburetor, downstream of the usual air filter, to which it is connected through channel 14, tank 6 and a conduit 16.

Injector 13 is located in a chamber 17 which communicates with induction pipe 1, downstream of the throttle valve 2, through an orifice 18 in line with the injector. Chamber 17 normally communicates with the atmosphere, possibly through the air intake 15, by means of an orifice 19 of a cross-section considerably greater than that of orifice 18 so that the pressure existing normally in chamber 17 is either the atmospheric pressure itself or the pressure existing in the air intake 15.

Fuel under pressure is therefore injected through orilice 18 into induction pipe 1, and advantageously the liquid jet thus injected is deflected by a surface 20 making with the axis of pipe 1 an angle of approximately 45, which further atomizes said jet of liquid.

Now, according to the present invention, such a carburation device is provided with means capable, when the device is working close to idling running conditions, of establishing upstream of injector 13, that is to say in conduit 12, a pressure substantially equal to the pressure existing in air intake 15 and also advantageously means capable of producing in chamber 17 a suction which depends upon that existing in induction pipe 1 downstream of throttle valve 2, so that the carburation device then works in the same manner as a conventional carburetor having a constant level chamber.

The above mentioned means are advantageously operatively connected with the means for controlling throttle valve 2 or with a device responsive to the pressure existing in induction pipe 1 or in conduit 12.

In order to provide, upstream of injector 13, a pressure substantially equal to the pressure existing in the air intake 15, when the conditions correspond to idling running, the pressure regulator 10 is advantageously made in the form of an overflow constant level chamber further including a cover capable of limiting, in cooperation with the top edge of said'chamber, the above mentioned variable section leak passage, the abovementioned means being capable of sufliciently opening the passage in question, when the conditions are approximately the idling running conditions, so that the pressure existing in the constant level chamber is the same pressure as that existing in casing 11. In order to enable fuel to flow from said chamber toward the injector for conditions approximating idling running conditions and only in this case, the injector is located some millimeters above the overflow edge of the chamber.

Finally, in order to produce in chamber 17 a suction depending upon that existing in induction pipe 1 downstream of throttle valve 2, for conditions averaging the idling running conditions, the above mentioned means are arranged in such manner as to close or at least substantially to reduce the cross-section of the communication passage between chamber 17 and the atmosphere.

According to the embodiment illustrated by FIGS. 1 and 2, the pressure regulating device is essentially constituted by a chamber 21 provided with a top edge 22, which is for instance circular and horizontal. A cover 23, capable of being applied upon this edge, is guided by a rod 24 and a spring 25 constantly urges said cover in the upward direction.

Chamber 17 communicates with the atmosphere or with the air intake 15 not only through orifice 19 but also through an orifice 26 the communication of which with said chamber 17 may have its cross-section adjusted by means of an adjustable screw 27 cooperating with a calibrated orifice 28.

Injector 13 is located at a height H of some millimeters above the edge 22 of the chamber 21.

Close to cover 23 there is provided a lever 29 journalled aboutan axis 30. The end 290: of this lever is nearly constantly applied against cover 23-. It exerts thereon a force transmitted through a rod 31 secured to the end 29b of lever 29. This rod is connected to a diaphragm 32 forming the movable wall of a variable volume chamber 33 which may itself be connected through two successive channels 34 and 35 with the venturi passage 5. Of course, this diaphragm 32 might be replaced by bellows or even a piston.

The communication between channels 34 and 35 is not permanent and it may be of interest to vary the suction existing in chamber 33 with respect to that existing in the venturi passage by making use of other elements such as means for partly connecting these channels with the atmosphere or, on the contrary, means for exerting in chamber 33 a suction greater than that existing in venturi passage 5, according to the conditions of operation. For this purpose, use may be made of a distributing valve of any type, such as a rotary distributing valve 36 adapted to pivot about an axis 37 and applied against a plane surface into which channels 34 and 35 open at 38 and 39 respectively.

The distributing valve is provided with a groove 40 in the form of a circular arc and, preferably, with a hole 41 connected either with the atmosphere, or with air intake 15. The plane face of the distributor may also be provided with an orifice 42 connected with a channel 43 opening into suction pipe 1 slightly upstream of throttle valve 2 when said valve is closed, this orifice cooperating with a radial branch 40a of groove 40. Distributing valve 36 is operatively connected with throttle valve 2 through linkmeans 44, possibly with a semi-positive drive.

Means are provided for acting upon the cross-section of orifice 19, for instance by means of a lever 45 rotatable about an axis 46. Thislever 45 carries, at the end of its lower arm, a conical member 47 for closing orifice 19 whereas the end of the other arm of lever 45 is acted upon by a sliding rod 48 actuated by a l-aver' 49 rigid with throttle valve 2. A spring 50 constantly urges lever 45 in the anti-clockwise direction (with reference to FIGS. 1 and 2). A third arm of lever 45- may also serve to .4 connect this lever through a rod 51 to a closing valve 52 cooperating with an orifice 53 provided in channel 34.

Finally, a supplementary correcting device consists in a diaphragm 54 forming the movable wall of a variable volume chamber 55 connected, through a conduit 56, either as shown to channel 34 through chamber 3-3, or to any other portion of channels 34 and 35, or again to distributing valve 36 if this happens to be useful. This diaphragm 54 acts, through a rod 57, upon the end 290 of lever 29' in one direction, due to the fact that this rod 57 passes through a hole provided in the end 290 of lever 29 and is provided with an end abutment 58.

A spring 59 tends constantly to apply diaphragm 54 upon a fixed abutment, so that the suction acting in chamber 55 must exceed a given value in order to start diaphragm 54 moving toward the right hand side of FIGS. 1 and 2 and to bring abutment 58 into" contact with the end 290 of lever 29.

The carburation device above described works in the following manner:

As a rule, the pressure of the fuel fed through injector 13 must depend upon the flow rate of air through venturi passage 4. This flow rate is characterized by the suction existing either in venturi 4 or in venturi 5, which gives a higher accuracy and a greater suction. It suffices to vary the injection pressure suplied by the pressure regulator in accordance with the suction existing in venturi passage 5. For this purpose, the suction existing in the venturi passage is normally transmitted in chamber 33 and exerts an upward pull upon diaphragm 32 and rod 31. The end 29a of lever 29 then exerts upon cover 23 a downward force which depends upon the flow rate of air through the main venturi passage 4. The excess of fuel passes through the annular space existing between the top edge 22 of chamber 21 and cover 23, so that the residual pressure existing in the pressure regulator 10 depends essentially upon the suction existing in chamber 33. The excess of fuel is collected through channel 14 and flows back either to tank 6 or directly to the input of pump 7.

Under normal working conditions, and if it is supposed that throttle valve 2 is either partly or wholly open (FIG. 2), the injection pressure supplied at the nozzle of injector 13 depends upon the flow rate of air which is itself characterized by the suction existing in venturi passage 5. This is due to the fact that injector 13 opens into chamber 17 the orifice 19 of which is wide open because lever 45 is not being pushed by rod 48 and spring 50 urges lever 45 in the anti-clockwise direction, thus moving member 47 away from orifice 19. Furthermore, during this movement, valve 52 closes passage 53, or distributing valve 36 keeps orifices 38 and 41 isolated. Furthermore, this distributing valve is in a position such that groove 40 directly connect orifices 38 and 39, therefore transmitting to chamber 33 the suction existing in venturi passage 5.

For small openings of throttle valve '2 (positions intermediate between those of FIGS. 1 and 2), the orifice 42, which communicates at this time with the downstream side of throttle valve 2, transmits to groove 40, through its radial branch 40a, a small portion of the suction existing downstream of said throttle valve. The ratios of the cross-sectionof orifice 42 to those of orifices 38 and 39 are such that a suitable suction is transmitted to chamber 33.

When the conditions correspond to idling, that is to say when the throttle valve 2 is in its maximum closing position, or near this position (FIG. 1), the feed of fuel through injector 13 is extremely small and consequently must be determined by a very low pressure and this flow cover 23 is released from the action of lever 29, due to the fact that there is no appreciable suction in chamber 33. This cover 23 is therefore lifted, under the efiect of spring 25, to a relatively great distance above the top edge of chamber 21. The excess of fuel then overflows freely above the top edge 22 of this chamber. The fuel therefore has, in chamber '21, a constant level located at the height H below injector 13. This height H is equal to some millimeters as in conventional carburettors, but

there would be no flow of fuel if a sufficient suction were not produced in chamber 17 For this purpose, orifice '19. is closed by member 47 actuated by lever 45 which is itself rotated in the clock wise direction, against the action of spring 50, by rod 48 which is pushed by lever 49 rigid with the spindle 3 of throttle valve 2. In order to adjust the rate of feed of fuel, use is made of screw 27 the end of which is of conical shape, which cooperates with calibrated orifice 28 so as to permit of adjusting the suction existing in chamber 17, which pressure is determined by the ratio of the sections of orifice 18 on the one hand and of the orifice determined by screw 27 on the other hand.

A conventional device for adjusting the minimum opening of throttle valve 2, not shown by the drawing, determines the main air flow for idling running conditions, whereas the adjustment of screw 27 ensures, together with a small air flow through orifice 18, the flow rate of fuel necessary for feeding the engine under idling running conditions.

As, in such conditions, the flow rate of air in suction pipe 1, small as it maybe, might create in venturi passage 5 a very slight suction which would be transmitted to chamber 33, possibly through leaks in distributing valve 36, thus preventing the full opening of cover 23, means must be provided for preventing the existence of such a suction. Two such means have been shown on FIGS. 1 and 2, one in solid lines and the other in dotted lines. The first solution consists in providing, in distributing valve 36, an orifice 41 communicating with the atmosphere or with the air intake 15 and which comes over orifice 38 so as to establish a relative Zero pressure in chamber 33 (FIG. 1). Another solution consists in causing lever 45 to act upon valve 52 which, when orifice 19 is closed, simultaneously opens orifice 53 so as to place chamber 33 in communication either with the atmosphere or with the air intake 15.

A supplementary correction device has been shown on FIGS. 1 and 2. It is known that, when the engine is running at high speeds and closed to its maximum power, it is often necessary to increase the richness of the mixture fed to said engine and, consequently, it is necessary to make use of a device producing an increase of the flow rate of fuel with respect to that which would be produced merely by the normal suction existing in venturi passage 5. For this purpose, diaphragm 54 is subjected to a suitable suction, for instance that existing also in venturi passage 5 and transmitted through channels 35, 34 and 56, this suction acting against the action of spring 59 which prevents the diaphragm from moving before a predetermined suction has been reached which corresponds to the air flow rate for which the correction device must enter into action.

When this flow rate is reached, the suction existing in venturi passage 5 becomes suificient to pull diaphragm 54 toward the right against the action of spring '59, which moves rod 57 and its abutment 58 also toward the right of FIG. 1 so that abutment 58 comes into contact with lever 29 at the end 290 thereof. This action is then added to that of diaphragm 32 and the pressure determined by the pressure regulator further increases and becomes more important than if it had been determined solely by diaphragm 32. This corresponds to an increase of the flow rate through injector 13 and consequently to an en richment of the air and fuel mixture.

When passing gradually from idling running conditions ('FIG. 1) to normal running conditions (FIG..2), the flow rate of air through pipe 1 increases and the flow rate of fuel through injector 13 must also increase. This increase of the flow rate of fuel is normally produced by the fact that the pressure upstream of the injector passes from a negative value, due to the difierence of height H, to a positive value due to the action of pressure regulator 10 under the effect of a partial closing of cover 23. Now, it may happen thatthe pressure regulator Works with some inertia and that the pressure upstream of injector 13 practically does not change when the throttle valve 2 is moved from the idling running position of FIG. 1 to a position Where it is slightly opened.

In order to obviate this drawback, it is advantageous to provide means for first reducing the cross-section through which chamber 17 is vented before this crossseotion is increased to the value necessary to establish in this chamber a pressure substantially equal to atmospheric pressure, as throttle valve 2 is opened from the idling running condition. In this way, the desired increase of flow rate for positions of small opening of the throttle valve is produced or accentuated by the increase of suction existing in chamber 17. Such means may be operated either, as shown by FIG. 3, by means of lever 45, or by means of distributing valve 36, or again by both of these parts acting simultaneously.

For this purpose, according to the modification of FIG. 3, on the one hand the closing member 47 of FIGS. 1 and 2 is replaced by a rod 60 connected to the lower end of lever 45 and carrying a needle 61 of suitable shape, for instance of biconioal shape, and on the other hand the orifice 19 of FIGS. 1 and 2 is replaced by a calibrated orifice 62 in which said needle is movable.

Under idling running conditions, needle 61 occupies the position shown by FIG. 3 Where the orifice 62 is only partly closed. When throttle valve 2 is brought to a position where it is only slightly opened, needle 61 moves toward the right of FIG. 3 and gradually reduces the cross-section of the annular passage existing between said needle and orifice 62, which increases the suction existing in chamber 17 and consequently the flow rate of the fuel, even if the pressure upstream of injector 13 has not yet been increased by pressure regulator 10. Then, when the throttle valve is brought into intermediate opening positions and large opening positions, needle 61 is moved to a greater distance toward the right and fully clears orifice 62, the conditions of operation then becoming the same as shown by FIG. 2. The pressure regulator has then been given time to produce the necessary injection pressures.

It may happen that there is only one pressure regulater and that two or several injectors such as 13 are provided which are at relatively great distances from the pressure regulator. In this case, if the engine were tilted sufliciently due for instance to an inclination of the vehicle, one or several of the injectors might in fact be placed below the constant level determined by overflow of fuel in the pressure regulator 10. This would cause a permanent fiow through said injector or a detrimental enrichment of some injectors as compared with the others.

In order to avoid this drawback, the device may be arranged as shown by FIG. 4. In this case, chamber 21 is disposed at an angle of approximately 45 with re spect to the vertical and conduit 12 which feeds to injectors 13 is provided with an orifice 63 which opens into said chamber. When cover 23 is in a position corresponding to idling running conditions, the level of fuel in the chamber corresponds to a horizontal line such that orifice 63 opens into air; The suction through injeotor 13 and conduit 12 causes a mixture of fuel and air to be formed at the level of orifice 63 and, consequently, the height H actually becomes that indicated on FIG. .4 by H and which remains constant whatever he the level of injectors '13 with respect to the pressure regulator 10.

FIG. shows a modification of the device acting upon pressure regulator 10 as a function of the air flow rate in pipe 1. According to this modification, the law of operation of the regulator is corrected if necessary, and more particularly under full load running conditions, not by adding a supplementary force to that exerted by diaphragm 32, but by making use of a diaphragm 32 capable of applying to rod 31 a force that would be too great if the whole of the suction existing in venturi passage 5 were transmitted to chamber 33, and by reducing, to a value corresponding to every condition of operation of the engine, the actual suction exerted in chamber 33.

For this purpose, chamber 33 is connected with channel 34 through a calibrated orifice 64 and is provided with an orifice 65 through which can move a needle 66 of suitable longitudinal section, connected to a diaphragm 67. This last mentioned diaphragm forms a partition between a chamber 68 connected, through orifice 69, to the outside or to the air intake and a chamber 70 connected through a channel 35a to a suitably chosen point of induction pipe 1 either upstream or downstream of throttle valve 2. Generally, this channel 35a is connected through channel 35 to venturi passage 5. A spring 7 1 constantly urges diaphragm 67 in the downward direction of FIG. 5. Distributing valve 36 has been shown on this FIGURE 5, but in this case it might be dispensed with. However, it has been preferred to show the maximum of possibilities for performing all the corrections necessary to obtain a good carburation, in view of the fact that all these devices may be used either separately or simultaneously, without any drawback.

The operation is as follows:

The pressure of the fuel is in the usual manner determined by the action of diaphragm 32 acting through rod 31 and lever 29 upon the cover 23 of the pressure regulator 10. For every value of the suction existing in venturi passage 5, diaphragm 67 and consequently needle 66 occupy a well determined position, which makes it possible, owing to the particular shape of the longitudinal section of needle 66, to determine, for every working condition, the area of the free section of annular orifice 65 which, in combination with the constant cross section orifice 64, determines in chamber 33 a resultant suction which permits of obtaining exactly the desired pressure for the fuel fed through injector 13. Of course, the Whole of a needle such as 66 and a diaphragm such as 67 might be replaced by any equivalent distributing device, either a pivoting one or a sliding one, etc.

FIG. 6 shows a system for closing chamber 17 which is more accurate than that shown with reference to the preceding embodiments. In these embodiments, chamber 17 was closed by mechanical devices operatively connected with throttle valve 2. Since, as a rule, the closing of this chamber 17 must take place in relation with the pressure of the fuel fed through injector 13, that is to say with the pressure existing in conduit 12, it is advantageous to control the closing or opening of this chamber 17 by the effect of the pressure existing in conduit 12.

For this purpose, chamber 17 is provided at its end with a valve seat 72 cooperating with a valve element 73, itself carried by a diaphragm 74 forming the movable wall of a variable volume chamber 75 connected through a channel 76 with conduit 12. A spring 77 acts in the suitable direction and as a rule against the action of the pressure existing in chamber 75. Orifice 19 is the air port through which air is fed to valve seat 72, said orifice 19 being in communication either with the outside aemosphere, or with the air intake 15.

It will be seen that it cover 23 is lifted so as to reduce to zero the pressure of the fuel in conduit 12, spring 77 becomes preponderating and pushes back diaphragm 74 so that valve element 73 is applied against its seat 72. The conditions are then those corresponding to idling running where some suction is exerted on the orifice of injector 13. As soon as the pressure regua later 10 is again in operation, that is to say sends fuel under pressure through conduit 12, diaphragm 74 acts against the action of spring 77 and instantaneously opens the space between valve element 73and valve seat 72 so as to supply a practically constant pressure in chamber.

' FIG. 7 shows other accessory devices. In the first place, a device is provided to ensure pick-ups, that is to say the feed of a suflicient amount of fuel to provide a suitable richness of the mixture in case of sudden opening of throttle valve 2.

.As a matter of fact, if no special device is provided there is a risk that a sudden opening of this throttle valve will permit air to pass immediately whereas the fuel pressure will rise but slowly after a suitable suction is established in venturi passage 5 and is transmitted into chamber 33. This may produce a delay during which the operation of the internal combustion engine is defective. The device above referred to is therefore intended, when the throttle valve 2 is suddenly opened, immediately to increase the fuel pressure supplied through injector 13.

For this purpose for instance, lever 29 carries a cylinder 78 open at the top and closed at the bottom, either in a permanent manner, or by means of a check-valve 79-closing an orifice 80. This cylinder 78 contains a piston 81 movable therein and connected through a link 82 wih a level 83 pivoting about an axis 84. One end of lever 83 is connected through a rod 85 with a lever 86 rigid with throttle valve 2. Thechamber 87 of cylinder 78 is always filled with liquid, for instance through a tube 88 connected to conduit 9 and through which liquid flows permanently to the space above piston 81 and cylinder 78 between which a radial play is provided, the excess of fuel returning through channel 14 to the fuel tank.

When throttle valve 2 is suddenly opened from the idling running position shown by FIG. 7, there is produced a compression of the liquid present in chamber 87 which immediately causes cover 23 to be closed and the establishment of a pressure in channel 12, this pressure being much higher than that necessary for permanent working conditions. This high pressure is only temporary because when the movement of throttle valve 2 is stopped, the fuel contained in chamber 87 flows through the radial play provided between piston 81 and cylinder 78, and lever 29 returns to the position given thereto by diaphragm 32. On the contrary, when throttle valve 2 is suddenly closed, two kinds of operation are possible. Either the lower part of chamber 87 is permanently closed and there is obtained a movement inverse of that above described and which consists in eliminating in a single stroke the pressure in conduit 12, thus cutting off the feed of fuel during the deceleration preiod, which permits a far from negligible economy of fuel. Or a check-valve 79 is provided as shown by the drawing cooperating with an orifice 80, and this in order to avoid a retaining movement which would prevent the quick closing of the throttle valve 2, liable to produce accidents. It is possible to combine these two solutions by making use, instead of a rigid rod 85, of a semipositive connection with a spring which would ensure a safer operation.

This FIG. 7 shows a modification of the venting of the space inside casing 11 directly through an orifice 89 which may be connected either with the atmosphere, or with the main air intake of the carburation device.

A last device shown by FIG. 7 consists in providing an orifice 90 which may place conduit 12 in communication with the outside and which cooperates with a valve 91 actuated by a diaphragm 92. This diaphragm 92 constitutes the movable wall of a' variable volume chamber 93 communicating, through a channel 94, with the induction pipe 1 of the engine downstream of the throttle valve 2 thereof. This diaphragm 92 cooperates with a spring 95 in such manner that orifice 90 can be opened only in the case where the suction in chamber 93 is higher than that corersponding to idling running conditions.

With such an arrangement, when the internal combustion engine is driven by the motor car at high speeds, injector 13 is put out of operation, which prevents the flow of fuel. As a matter of fact, in this case, throttle valve 2 is quite closed, cover 23 is opened, no pressure is exerted on the fuel in conduit 12 and the injector would thus feed fuel only under the effect of suction. If orifice 90 is opened, this flow of fuel is prevented, which permits a supplementary saving of fuel and avoids the formation of non burnt gases or of decomposition products corresponding to a bad combustion, which are particularly noxious products.

In a general manner, while I have, in the above description, disclosed what I deem to be practical and efiicient embodiments of my invention, it should be well understood that I do not wish to be limited thereto as there might be changes made in the arrangement, disposition and form of the parts without departing from the principle of the present invention as comprehended within the scope of the accompanying claims.

What I claim is:

1. An internal combustion engine carburation device which comprises, in combination, an induction pipe having an air intake, a throttle valve mounted in said induction pipe downstream of said air intake, nozzle means for injecting fuel into said induction pipe downstream of said throttle valve, a fuel feed conduit leading to said injecting nozzle means, a fuel chamber open at the top having a top edge for overflow of fuel, said conduit starting from said chamber at a point thereof below its top, a fuel tank, means forming a communication between said fuel tank and said chamber, a continuous flow fuel pump in said communication adapted to supply said chamber with fuel at a rate at least equal to the maximum flow rate through said fuel feed conduit, whereby fuel may escape from said chamber over the top edge thereof, a cover movably mounted above said. top edge, and means responsive to variation of the flow rate of air through said induction pipe for controlling the position of said cover so as to limit, under normal running conditions, a restricted passage between said cover and said chamber top edge, whereby a pressure is maintained in said chamber in accordance with the air flow rate through said induction pipe, said last mentioned means being adjusted to bring said cover, under idling running conditions, to such a height above said top edge that fuel overflows freely at said top edge, said top edge being at a level lower than that of said injecting nozzle means so that said nozzle means are then fed, under the effect of the suction in said induction pipe, from said chamber acting as a conventional constant level tank of the overflow type.

2. An internal combustion engine carburation device which comprises, in combination, an induction pipe having an air intake, a throttle valve mounted in said induction pipe downstream of said air intake, nozzle means for injecting fuel into said induction pipe downstream of said throttle valve, a fuel feed conduit leading to said injecting nozzle means, a casing limiting a space in communication with said air intake, a fuel chamber located in said casing, said chamber being open at the top and having a top edge for overflow of fuel, said conduit starting from said chamber at a point thereof below its top, a fuel tank, means forming a communication between said fuel tank and said chamber, a continuous flow fuel pump in said communication adapted to supply said chamber with fuel at a rate at least equal to the maximum flow rate through said fuel feed conduit, whereby fuel may escape from said chamber over the top edge thereof, a cover movably mounted above said top edge, and means responsive to variation of the flow rate of air through said induction pipe for controlling the position of said cover so as to limit, under normal running conditions, a restricted passage between said cover and said chamber top edge, whereby a pressure is maintained in said chamber in accordance with the air flow rate through said induction pipe, said last mentioned means being adjusted to bring said cover, under idling running conditions, to such a height above said top edge that fuel overflows freely at said top edge, said top edge being at a level lower than that of said injecting nozzle means so that said nozzle means are then fed, under the effect of the suction in said induction pipe, from said chamber acting as a conventional constant level tank of the overflow type.

3. An internal combustion engine carburation device which comprises, in combination, an induction pipe having an air intake, a venturi passage in said induction pipe downstream of said air intake, a throttle valve mounted in said induction pipe downstream of said venturi passage, nozzle means for injecting fuel into said induction pipe downstream of said throttle valve, a fuel feed conduit leading to said injecting nozzle means, a fuel chamber open at the top having a top edge for overflow of fuel, said conduit starting from said chamber at a point thereof below its top, a fuel tank, means forming a communication between said fuel tank and said chamber, a continuous flow fuel pump in said communication adapted to supply said chamber with fuel at a rate at least equal to the maximum flow rate through said fuel feed conduit, whereby fuel may escape from said chamber over the top edge thereof, a cover movably mounted above said top edge, resilient means for urging said cover upwardly, means forming a variable volume box having a movable wall, and means placing the inside of said box in communication with the inside of said venturi substantially at the throat thereof, means operatively connecting said movable wall with said cover for urging said cover downwardly so as to limit, under normal running conditions, a restricted passage between said cover and said chamber top edge, whereby a pressure is maintained in said chamber in accordance with the suction at said throat of said venturi passage, said last mentioned means being adjusted to lift said cover, under idling running conditions, to such a height above said top edge that fuel overflows freely at said top edge, said top edge being at a level lower than that of said injecting nozzle means so that said nozzle means are then fed, under the effect of the suction in said induction pipe, from said chamber acting as a conventional constant level tank of the overflow type.

4. An internal combustion engine carburation device which comprises, in combination, an induction pipe having an air intake, a venturi passage in said induction pipe downstream of said air intake, a throttle valve mounted in said induction pipe downstream of said venturi passage, nozzle means for injecting fuel into said induction pipe downstream of said throttle valve, a fuel feed conduit leading to said injecting nozzle means, a fuel chamber open at the top having a top edge for overflow of fuel, said conduit starting from said chamber at a point thereof below its top, a fuel tank, means forming a communication between said fuel tank and said chamber, a continuous flow fuel pump in said communication adapted to supply said chamber with fuel at a rate at least equal to the maximum flow rate through said fuel conduit, whereby fuel may escape from said chamber over the top edge thereof, a cover movably mounted above said top edge, resilient means for urging said cover upwardly, means forming a variable 'volume box having a movable wall, means placing the inside of said box in communication with the inside of said venturi substantially at the throat thereof, means operatively connecting said movable wall with said cover for urging said cover downwardly so as to limit, under normal running conditions, a restricted passage between said cover and said chamber top edge, whereby a pressure is maintained in said chamber in accordance with the suction at said throat of said venturi passage, said last mentioned means being adjusted to lift said cover, under idling running conditions, to such a height above said top edge that fuel overflows freely at said top edge, said top edge being at a level lower than that of said injecting nozzle means so that said nozzle means are then fed under the effect of the suction in said induction pipe, from said chamber acting as a conventional constant level tank of the overflow type, and means interposed between said venturi passage throat and the inside of said box and operatively connected with said throttle valve for varying the suction in said box in accordance with the degree of opening of said throttle valve.

5. A carburation device according to claim 4 further including means for placing the inside of said box in communication with the atmosphere when said throttle valve is near its maximum closing position.

6. A carburation device according to claim 4 in which said last mentioned means are adapted to increase the suction action in said box when said throttle valve is near its maximum opening position.

7. A carburation device according to claim 1 in which the top edge of said chamber is inclined with respect to the horizontal, said fuel feed conduit opening at its lower end into said chamber at a level below the overflow level of said top edge, said fuel feed conduit being provided with a small orifice opening into said chamber above said overflow level.

-8. A carburation device according to claim 1 further including, for controlling the position of said cover, in addition with said means responsive to variation of the flow rate of air through said induction pipe, a mechanism operatively connected with said throttle valve and adapted suddenly and temporarily to apply said cover on said top edge Whensaid throttle valve is suddenly opened.

9. An internal combustion engine carburation device which comprises, in combination, an induction pipe, a throttle valve movably mounted in said induction pipe, said induction pipe being provided, at a point thereof downstream of said throttle valve, with a fuel injection hole, means forming on the outside of said induction pipe an air chamber adjoining said pipe and communicating through said hole with the inside of said pipe, a fuel feed conduit extending into said chamber, the end of said conduit forming a nozzle located in said chamber in line with said hole, the cross-sectional area of said nozzle being smaller than that of said hole, said air chamber being provided with an orifice of large crosssection placing the inside of said air chamber in communication with the atmosphere, pressure regulating means for normally applying to the fuel in said feed conduit a pressure varying in direct relation to the flow rate of air through said induction pipe, means responsive to the closing of said throttle valve into idle running position for transforming said pressure regulating means in a constant level fuel chamber so that fuel is then fed to said nozzle essentially by the suction then acting on said nozzle and means also responsive to the closing of said throttle valve into idle running position for reducing the cross-section area of said orifice when said throttle valve is so closed so as to produce in said air chamber a suction resulting from that existing in said induction pipe downstream of said throttle valve.

10. A carburation device according to claim 9 in which said last mentioned means are mechanical means operatively connected with said throttle valve.

11. A carburation device according to claim 9 in which said last mentioned means are hydraulic means operative by the fuel present in said fuel feed conduit.

12. A carburation device according to claim 9 in which said last mentioned means are adapted to reduce the cross-section of said orifice before opening it in response to the opening of said throttle valve from its idle running position.

13. A carburation device according to claim 1 further including means responsive to the suction existing in said induction pipe downstream of said throttle valve for producing a leak in said fuel feed conduit for values of said suction exceeding a given value so as to cut off any feed of fuel to said induction pipe when the internal combustion engine on which the carburation device is mounted is running at high speed with its throttle valve closed.

References Cited in the file of this patent UNITED STATES PATENTS 2,809,022 Chandler Oct. 8, 1957 

